Finally found it!
My mom made this cake for my birthday a couple of months ago and my DIL loved it so much ... I am making some for her baby shower. It was at this great blog:
I'll share the other recipes and ideas from the shower when I have more time!
TRES LECHES CAKE
1 package white cake mix, plus ingredients to prepare mix
1 can (14 ounces) sweetened condensed milk
1 cup milk
1 cup (1/2 pint) whipping cream
1 container (8 ounces) whipped topping, thawed
Preheat oven to 350F. Spray a 13x9x2-inch baking pan with nonstick cooking spray.
Prepare cake mix according to package directions. Bake about 35 to 40 minutes or until cake is firm to the touch. Remove cake from oven; cool 5 minutes.
Meanwhile, combine sweetened condensed milk, milk and whipping cream in a 4-cup measure. Poke holes all around the warm cake, using a wooden skewer or toothpick. Slowly pour milk mixutre evenly over top of holes on cake. Let cake cool 10 to 15 minutes more to absorb all the liquid. Cover and refrigerate cake in pan at least 1 hour.
When cake is completely cool, spread whipped topping evenly on top. Cut into pieces and serve with fresh fruit. Keep cake covered and refrigerated.